1. Field of the Invention
The present invention relates to a positioning apparatus and, more particularly, to a positioning apparatus for use preferably in an exposure apparatus used in manufacturing a semiconductor or liquid crystal device.
2. Description of the Related Art
An exposure apparatus for manufacturing a semiconductor or liquid crystal device has a reticle stage and a wafer stage for use in positioning a reticle (mask) as an original plate and a wafer as a substrate. “Ultraprecision Manufacturing Technology, Vol. 3: Technology of Measurement and Control” (the first edition, Jul. 15, 1995, issued by Fuji Technosystem, pp. 20-27, supervised by Akira Kobayashi) discloses a method of disposing a stage moving with a large stroke (coarse motion) and a stage moving with a small stroke (fine motion) to carry out high-precision positioning in this type of stage apparatus (positioning apparatus).
FIGS. 8A and 8B are diagrams showing a stage apparatus having a coarse and fine motion mechanism described in Japanese Laid-Open Patent Publication (Kokai) No. 2000-106344. A support frame 306 (coarse motion stage) connected to a movable section 311 of a feed screw system 310 moving with a large stroke is movable on a plane guide 302. The feed screw system also includes a feed screw 313 and a motor 312. The support frame 306 is provided with a linear motor stator 305 for moving with a small stroke and generates a force between the support frame 306 and a stage 301 (a fine motion stage) provided with a linear motor mover 304, thereby enabling the stage 301 to move finely relative to the support frame 306.
The support frame 306 is further provided with a pair of electromagnets 308 such that the stage 301 is put between the electromagnets 308 in a Y-axis direction. It generates an attraction between the pair of electromagnets 308 and a magnetic plate 307 provided on the stage 301, thereby functioning as an electromagnetic coupling. When the support frame 306 accelerates or decelerates at the maximum velocity, it transmits a force to the stage 301 by using an attraction of one of the pair of electromagnets 308.